In order to write a normative statement or conformance clause using RFC2119 language, the target or subject of the rule needs to be included. Some of these are obvious, as we have rules governing components, composites, services, references etc. Other targets are less so, especially when it comes to conformance, as we need to identify artefacts that vendors can claim they handle according to the rules of the spec. We should enumerate a list of conformance targets early on, so that every time we use a MUST, MAY, or SHOULD, we know to what the rule applies to.